A material, usually a crystal, whose conductivity lies somewhere between that of an electric conductor, such as a metal, and that of an insulator, such as rubber. A semiconductor may be a pure metal, such as silicon or germanium, or a compound such as gallium arsenide or indium phosphide. The electrical characteristics of an intrinsic semiconductor depend solely on a pure crystal, while those of an extrinsic semiconductor rely on dopants which are introduced. In a p-type semiconductor trivalent dopants are added to increase conductivity, while pentavalent dopants are added to enhance the conductivity n-type semiconductors. mobile electrons, holes, or ions transport charges through semiconductors. Used extensively to make semiconductor devices. Also called semiconductor material.